Most tissues exist in a highly regulated dynamic equilibrium wherein new tissue is formed and existing tissue is degraded and eliminated. The degradation of the extracellular matrix (ECM), including connective tissue and basement membranes, is effected by the metalloproteinases which are released from connective tissue and invading inflammatory cells. Excessive unregulated activity of these enzymes can result in undesirable tissue destruction and their activity is regulated at the transcription level, by controlled activation of the latent proenzyme and, after translation, by intracellular specific inhibitory factors such as TIMP (“Tissue Inhibitors of MetalloProteinase”) or by more general proteinase inhibitors such as α2-macroglobulins.
Several structurally related metalloproteases (MPs) are known to play an important role in the breakdown of structural proteins. These metalloproteases typically act on the intercellular matrix, and thus are involved in tissue breakdown and remodeling. Such proteins have been referred to as metalloproteases or MPs. There are several different families of MPs, classified by sequence homology. Several families of known MPs, as well as examples thereof, are disclosed in the art.
These MPs include Matrix-Metallo Proteases [MMPs], zinc metalloproteases, many of the membrane-bound metalloproteases, TNF converting enzymes, angiotensin-converting enzymes (ACEs), disintegrins, including ADAMs (See Wolfsberg et al, 131 J. Cell Bio. 275-78 Oct. 25, 1995), and the enkephalinases. Examples of MPs include human skin fibroblast collagenase, human skin fibroblast gelatinase, human sputum collagenase, aggrecanase and gelatinase, and human stromelysin. Collagenase, stromelysin, aggrecanase and related enzymes are thought to be important in mediating the symptomatology of a number of diseases.
Zinc proteases are subdivided according to the primary structure of their catalytic sites and include gluzincin, metzincin, inuzincin, carboxypeptidase, and DD carboxypeptidase subgroups (Hooper N M, 1994, FEBS Lett, 354:1-6). The metzincin subgroup is further divided into serralysins, astacins, matrixins, and adamalysins (Stocker W and Bode W, 1995, Curr Opin Struct Biol, 5:383-390).
The matrixins include the matrix metalloproteases, or MMPs. MMPs constitute a family of structurally similar zinc-containing metalloproteases, which are involved in the remodeling and degradation of extracellular matrix proteins, both as part of normal physiological processes and in pathological conditions. For a review see Bode, W et al., 1996, Adv Exp Med Biol, 389:1-11. Connective tissue, extracellular matrix constituents and basement membranes are the biological materials that provide rigidity, differentiation, attachment sites and, in some cases, elasticity to biological systems. Connective tissue components include, for example, collagen, elastin, proteoglycans, fibronectin and laminin that form the scaffold for all human tissues. Under normal conditions, connective tissue turnover and/or repair processes are controlled and in equilibrium. The loss of this balance, for whatever reason, leads to a number of disease states. Inhibition of the enzymes responsible for loss of equilibrium provides a control mechanism for this tissue decomposition and, therefore, a treatment for these diseases. The uncontrolled breakdown of connective tissue by metalloproteases is a feature of many pathological conditions.
Besides a role in the regulation of extracellular matrix, there is also evidence to suggest that MMPs mediate the migration of inflammatory cells into tissues (Moscatelli D and Rifkin D B, 1988, Biochim Biophys Acta, 948: 67-85). Several reports have demonstrated that various MMPs can activate a variety of important non-matrix proteins, including cytokines, chemokines, integrins, and antimicrobial peptides (see Parks W C, 2002, J Clin Invest, 110:613-4). Many of the human MMPs are over-expressed in human tumors and are associated with peritumor tissue degradation and metastasis formation. Another important function of certain MMPs is to activate various enzymes, including other MMPs, by cleaving the pro-domains from their protease domains. Thus some MMPs act to regulate the activities of other MMPs, so that over-production of one MMP may lead to excessive proteolysis of extracellular matrix by another. It has also been reported that MMPs can cleave and thereby inactivate the endogenous inhibitors of other proteinases such as elastase (Winyard P G et al., 1991, FEBS Letts, 279: 91-94). Inhibitors of MMPs could thus influence the activity of other destructive proteinases by modifying the level of their endogenous inhibitors. In addition, increasing or maintaining the levels of an endogenous or administered serine protease inhibitor supports the treatment and prevention of diseases such as emphysema, pulmonary diseases, inflammatory diseases and diseases of aging (such as loss of skin or organ stretch and resiliency.) Thus, MMPs should not be viewed solely as proteinases of ECM catabolism, but rather as extracellular processing enzymes involved in regulating cell-cell and cell-ECM signaling events.
The adamalysins include the reprolysins, snake venom metalloproteases and the ADAMs. The ADAMs (a disintegrin and metalloprotease domain) are an important family of metalloproteases. They are a family of type I transmembrane glycoproteins that are important in diverse biologic processes, such as cell adhesion and the proteolytic shedding of cell surface receptors. ADAM family members have been identified from mammalian and non-mammalian sources, including Xenopus, Drosophila, and Caenorhabditis elegans. Members of the family have a modular design, characterized by the presence of metalloprotease and integrin receptor-binding activities, and a cytoplasmic domain that in many family members specifies binding sites for various signal-transducing proteins. The ADAMs family has been implicated in the control of membrane fusion, cytokine, growth factor and growth factor receptor shedding, and cell migration, as well as processes such as muscle development, fertilization, neurogenesis, and cell fate determination. Loss of regulation can lead to disease and pathology. Pathologies such as infertility, inflammation and cancer have been shown to involve ADAMs family members. For a review, see Wolfsberg T G and White J M, 1998, ADAM metalloproteinases. In Handbook of Proteolytic Enzymes (Barrett A J, Rawlings N D and Woessner J F eds), p. 1310-1313, Academic Press, London as well as Seals D F and Courtneidge S A, 2003, Genes and Development, 17:7-30.
Some specific examples of important ADAM metalloproteases include the TNFα-converting enzyme, TACE or ADAM17, that is currently an important target for anti-inflammatory drugs (Moss M L et al., 2001, Drug Discov Today, 6:417-426 and Black R A, 2002, Int J Biochem Cell Biol, 34:1-5). Other members of the family are also likely to be good therapeutic targets. ADAM8 has been reported to be expressed almost exclusively in cells of the immune system, particularly B-cells, monocytes, eosinophils and granulocytes. ADAM8 therefore represents a therapeutic target for human immunologically-based diseases. ADAM15 is found in human aortic smooth muscle and cultured umbilical vein endothelial cells. While ADAM15 is not expressed in normal blood vessels, it has been detected in developing atherosclerotic lesions (Herren B et al., 1997, FASEB J, 11:173-180), and has also been shown to be up-regulated in osteoarthritic versus normal human cartilage (Bohm B B et al., 1999, Arthritis Rheum, 42:1946-1950). Thus ADAM15 may play a role in atherosclerosis and cartilage degenerative diseases. In addition, ADAM15 knockout mice have reduced neovascularization and smaller tumors compared to wildtype controls, suggesting that ADAM15 may also be important in cancer (Horiuchi, K et al., 2003, Mol Cell Biol, 23:5614-5624.) The lymphocyte-specific expression of the ADAM28 suggests that it may have an important immunological function.
Excessive production of IgE is believed to be a major mediator of allergic responses. CD23, the low affinity receptor for IgE, is subject to ADAM-type metalloprotease-dependent proteolytic release of soluble extracellular fragments, which have been shown to cause upregulation of IgE production and induction of inflammatory cytokines (see Novak N et al, 2001, Curr Opin Immunol, 13:721-726 and Mayer R J et al., 2002, Inflamm Res, 51:85-90). Increased levels of soluble CD23 have been observed in allergic asthma, in chronic B-lymphocytic leukemia and in rheumatoid arthritis. Inhibition of the enzyme(s) responsible for CD23 processing may offer a therapeutic approach for the treatment of various immune-based diseases. ADAM metalloproteases also appear to be responsible for the release or shedding of soluble receptors (for example, CD30 and receptors for TNF), adhesion molecules (for example, L-selectin, ICAM-1, fibronectin), growth factors and cytokines (for example Fas ligand, TGF-α, EGF, HB-EGF, SCF IL-6, IL-1, TSH and M-CSF), and growth factor receptors (for example EGFR family members, such as Her-2 and Her-4, which have been implicated in the pathogenesis of different types of cancer) (Yarden Y and Sliwkowski M X, 2001, Nature Reviews 2:127-137). For example, Her-2 is over-expressed in 25-30% of human breast cancers and is associated with an increased risk of relapse and death (Slamon D J et al, 1987, Science, 235:177-182). ADAM17 has recently been shown to be critical for the regulated shedding of Her-4 (Rio C et al, 2000, J Biol Chem, 275:10379-10387). The protease responsible for Her-2 cleavage, known as Her-2 sheddase, is an unknown MMP that may also be a member of the ADAM family (Codony-Servat J et al, 1999, Cancer Res 59:1196-1201). Modulation of this activity might therefore have an important role in the modulation of human disease. For a review of the sheddase activity of ADAMs see Moss M L and Lambert M H, 2002, Essays Biochem, 38:141-153.
ADAM-TS (also shown as “ADAMTS”) proteases have been identified as members of the ADAM family. These proteins are novel in that they contain unique thrombospondin (TS) type I motifs in addition to some of the structurally conserved domains of other ADAM family members. The ADAM-TSs are also distinguished from the ADAMs by their lack of cysteine-rich, EGF-like, transmembrane, and cytoplasmic domains. ADAM-TS proteins have also been shown to be associated with a number of pathological or human disease states. For example, ADAMTS-1 is a tumor-selective gene expressed in colon tumor cells and is also an inflammation-associated protein. A human ortholog of ADAMTS-1, known as METH-1, and the related protein METH-2 have been recently shown to have antiangiogenic activity, and these or other ADAM-TS family members may play important roles in regulating vascular development. ADAMTS-2 has been implicated in the normal development of the skin. This enzyme was long known as procollagen N-proteinase, a proteinase that proteolytically removes amino peptides in the processing of type I and type II procollagens to collagens, and it was shown to be deficient in the skin of individuals with the inherited connective tissue disorder type VIIC Ehlers-Danros syndrome. ADAMTS-4 and ADAMTS-1 are known as aggrecanase-1 and -2 because of their ability to cleave specific sites in aggrecan, a proteoglycan that maintains the mechanical properties of cartilage. Progressive degradation and depletion of aggrecan has been implicated in degenerative joint diseases such as osteoarthritis and inflammatory joint diseases such as rheumatoid arthritis. For a review of the ADAM-TS metalloproteases see Tang B L, 2001, Int J Biochem Cell Biol, 33:33-44 and Kaushal G P and S V Shah, 2000, J Clin Invest 105:1335-1337.
The metalloproteases are one of the older classes of proteinases and are found in bacteria, fungi as well as in higher organisms. Many enzymes contain the sequence HEXXH, which provides two histidine ligands for the zinc, whereas the third ligand is either a glutamic acid (thermolysin, neprilysin, alanyl aminopeptidase) or a histidine (astacin). Other families exhibit a distinct mode of binding of the Zn atom. Metalloproteases have therefore been isolated from a number of prokaryotic and eukaryotic sources. Acidic metalloproteases have been isolated from broad-banded copperhead and rattlesnake venoms. Neutral metalloproteases, specifically those having optimal activity at neutral pH have, for example, been isolated from Aspergillus sojae. Alkaline metalloproteases, for example, have been isolated from Pseudomonas aeruginosa and the insect pathogen Xenorhabdus luminescens. Inhibition of microbial metalloproteases may lead to growth inhibition and represent an antibiotic strategy. Inhibition of metalloproteases associated with snake venom or insect toxicity may also lead to new therapeutic strategies.
Potential therapeutic indications of MP inhibitors have been discussed in the literature. See for example, U.S. Pat. No. 6,500,847 (Bayer Corporation), U.S. Pat. No. 6,268,379 (DuPont Pharmaceuticals Company), U.S. Pat. No. 5,968,795 (Bayer Corporation), U.S. Pat. No. 5,892,112 (Glycomed Incorporated and The University of Florida), and U.S. Pat. No. 5,872,152 (British Biotech Pharmaceuticals Limited).
Matrix metalloprotease inhibitors are useful in treating diseases caused, at least in part, by breakdown of structural proteins. Although a variety of MMP inhibitors have been prepared in the relevant field, there is a continuing need for potent matrix metalloprotease inhibitors useful in treating diseases caused, at least in part, by breakdown of structural proteins. Applicants have found that, surprisingly, the compounds of the present invention are potent metalloprotease inhibitors.